The biggest reason I’ve run into gardeners finding this to be controversial isn’t whether it is legal or not (in lots of places, it isn’t, so it could be removed at any time by the local municipality) but rather how healthy it is to be eating food so close to the road, bathed in things like exhaust. It may not be healthy to hang out near diesel fumes.
There are some very cool examples out there of pollinator gardens (flowers useful to local critters) and rain gardens in these tricky curbside areas. Pictured above is a rain garden. For anyone in the US, here’s a list of regional suggestions for pollinator gardens.
